1. Field of the Invention
The present invention relates generally to a method of creating and recording data management information for a rewritable recording medium, and more particularly, but not by way of limitation, to creation and recording of video object presentation order management data accompanied by editing presentation order of still or moving pictures recorded on the recording medium.
2. Description of the Related Art
Optical disks have come into wide use since the advent of compact disc (CD) and the demand for optical disks is expected to grow steadily with popularization of digital versatile disk (DVD). Optical disks include read-only disks such as CD-ROM and DVD-ROM, write-once disks such as CD-R and DVD-R, and rewritable disks such as CD-RW and DVD-RAM. The specification of DVD-RTRW, which is standard writing/reading format of a rewritable disk, has not released yet and standardization for the DVD-RTRW is under way.
As rewritable optical disks like DVD-RAM are of immensely large capacity, users may store a variety of data such as moving pictures, still pictures, audio data, and the like on a single recording medium. Each time a new data file is recorded on a rewritable recording medium, navigation information for locating the data file after recording is created and recorded along with the data file on the recording medium. The recorded navigation information is referred to whenever the relevant data file is accessed.
Navigation information regarding all data files stored on a recording medium is contained in a navigation data table as shown in FIG. 1, which is recorded as a single navigation data file on the recording medium. Accessing the recording medium entails loading the navigation data file into a memory, wherein the navigation data reside all the time. When recording a moving or still picture on the recording medium, the area in which the picture file will be recorded is determined with reference to the navigation information. Recording a picture file always accompanies creating management information regarding the recorded picture file and updating the navigation data file to include the newly created management information.
Management data pertaining to moving pictures comprise movie video object information (M_VOBI) and movie video object presentation order information (movie Cell Information or simply CI). Suppose that a moving picture file is composed of n movie video objects (M_VOBs) M_VOB#1xcx9cM_VOB#n as shown in FIG. 3. Since each M_VOB needs a M_VOBI and a CI, n M_VOBIs and n CIs are created in the same order that n M_VOBs are recorded. In FIG. 3, M_VOBI#1xcx9cM_VOBI#n correspond to M_VOB#1xcx9cM_VOB#n and C#2, C#4, . . . (shaded Cells in the box labeled ORG_PGC) correspond to M_VOB#1xcx9cM_VOB#n. The created M_VOBIs and CIs are stored in the movie A/V file information table (M_AVFIT) and the original program chain information table (ORG_PGCIT) of the navigation data shown in FIG. 1, respectively. As illustrated in FIG. 2a, Cell Information related to a movie VOB consists of several fields: Cell type (C_TY) indicating that the relevant VOB is moving picture data, the ID number of the relevant M_VOB (M_VOB_ID), the presentation start time (C_V_S_PTM) and presentation end time (C_V_E_PTM) of the relevant M_VOB, the index number of the text data connected with the CI (IT_TXT_N), and the index number of the thumbnail connected with the CI (THMNL_N).
When the recording medium is accessed, the navigation data file is read from the recording medium and loaded into a memory as mentioned before. If reproduction of a moving picture is requested, M_VOBIs and CIs relevant to the requested moving picture file are read from the M_AVFIT and ORG_PGCIT of the navigation data table, respectively. In reference to the M_VOBIs and CIs, the requested moving picture file can be located from the recording medium and reproduced.
On the other hand, management data pertaining to still pictures comprise still picture video object information (S_VOBI) and still picture video object presentation order information (still picture Cell Information or simply CI). Suppose that a still picture file is composed of n still picture video objects (S_VOBs) S_VOB#1xcx9cS_VOB#n as shown in FIG. 3. Since each S_VOB needs a S_VOBI and a CI, n S_VOBIs and n CIs are created in the same order that n S_VOBs are recorded. In FIG. 3, S_VOBI#1xcx9cS_VOBI#n correspond to S_VOB#1xcx9cS_VOB#n and C#1, C#3, . . . (not shaded Cells in the box labeled ORG_PGC) correspond to S_VOB#1xcx9cS_VOB#n. The created S_VOBIs and CIs are stored in the still picture A/V file information table (S_AVFIT) and the original program chain information table (ORG_PGCIT) of the navigation data shown in FIG. 1, respectively. As illustrated in FIG. 2b, Cell Information related to a still picture VOB consists of several fields: Cell type (C_TY) indicating that the relevant VOB is still picture data, the ID number of the relevant S_VOB (S_VOB_ID), the playback time (C_PB_TM), presentation start time (C_V_S_PTM), and still time (C_STILL_TM) of the relevant S_VOB, the index number of the text data connected with the CI (IT_TXT_N), and the index number of the thumbnail connected with the CI (THMNL_N).
The procedure for reproducing a still picture is similar to that for reproducing a moving picture. If reproduction of a still picture is requested, S_VOBIs and CIs relevant to the requested still picture file are read from the S_AVFIT and ORG_PGCIT of the navigation data table, respectively. In reference to the S_VOBIs and CIs, the requested still picture file can be located from the recording medium and reproduced.
The navigation data file is used in the same manner when movie or still picture files recorded on the recording medium are edited. If a user makes or edits a list of moving or still pictures to reproduce them in a preferred order, management data regarding the list are created with reference to the navigation data loaded into the memory. The management data consist of a series of CIs corresponding to the selected pictures, which forms a user-defined PGC (UD_PGC) to be stored in the user-defined program chain or PGC information (UD_PGCI) of the user-defined PGC information table (UD_PGCIT) shown in FIG. 1. UD_PGC#i is stored in UD_PGCI#i.
If reproduction of a play list of picture files is requested, the UD_PGC stored in the UD_PGCI corresponding to the requested play list is read from the UD_PGCIT of the navigation data in the memory. Then, the M_VOBIs and S_VOBIs corresponding to the CIs can be read from the M_AVFIT and S_AVFIT. Finally, the VOBs linked to the play list can be read out and the play list can be reproduced in reference to the VOBIs and CIs.
In the above method, the amount of the navigation data increases with the number of user-defined PGCs each of which contains information on a presentation order of VOBs, because each user-defined PGC is recorded in a user-defined PGCI in the navigation data table. It is an apparent drawback of the method, therefore, that the navigation data file may take excessive storage space as user-defined PGCs increase in number.
One possible solution to the above problem is to limit the maximum number of user-defined PGCs and the maximum number of CIs that a user-defined PGC can hold. This method, however, may give rise to other problems. Suppose that the number of CIs which a user-defined PGC can take is limited to N. In this case, some picture program to be reproduced continuously cannot be managed by a single user-defined PGC if the number of CIs contained in the picture program exceeds the prescribed bound N.
It is therefore a primary object of the present invention to provide a method of creating and recording presentation order management data for a rewritable recording medium, which enables effective control of the amount of presentation order management information needed for managing user-defined play lists in the limited maximum size of navigation data.
The method of creating and recording presentation order management information for a rewritable recording medium according to the present invention comprises steps of: creating information tables classified by the types of presentation order management of recorded data; checking the amount of presentation order management information contained in said information tables on the request of new presentation sequence; and controlling creation and record of new presentation order management information based on the result of said checking.
The information table utilized in the present invention comprises an original program chain information table and a user-defined program chain information table. The former table contains management information for reproducing recorded data in the recording order of the data, while the latter table contains management information for reproducing data in a user-preferred order. More specifically, the user-defined program chain information table contains presentation order information units for storing user-defined data presentation sequence and user-defined program chains each of which consists of a plurality of the presentation order information units. The method according to the present invention enables effective management of the amount of presentation order management data by controlling the maximum number of presentation order information units and the maximum number of user-defined program chains.